What building regulations apply to an extension?
Building regulations approval is needed for almost every extension, loft conversion, garage conversion and structural alteration, even when planning permission is not. The work is inspected at set stages by the council’s building control service or, in England and Wales, a registered building control approver, and a completion certificate is issued at the end. In Scotland a building warrant must be granted before work starts.
What do building regulations cover?
- Structure: foundations, beams, lintels and roof design.
- Fire safety: escape routes, fire doors, smoke alarms and separation from neighbours.
- Energy: insulation levels, glazing performance and heating controls.
- Ventilation: background and extract ventilation to control condensation.
- Drainage: new connections and building over or near sewers.
- Electrics: new circuits and work in bathrooms and kitchens.
- Access, safety glazing and stairs.
Full plans or building notice?
In England and Wales you can apply with full plans, which are checked and approved before work starts, or with a building notice for simpler jobs. We use full plans for extensions and lofts because it gives certainty before money is spent.
Why does the completion certificate matter?
The completion (or final) certificate shows the work met the regulations. Buyers’ solicitors ask for it when you sell, and missing certificates can delay or derail a sale. We make sure every notifiable part of the work is signed off.
Related projects
This guide is general information about building work in the UK, not legal or tax advice. Rules change, so check the current position for your property with the council, HMRC or a qualified adviser before relying on it.